The criteria for metabolic syndrome and the national health screening and education system in Japan

Two major definitions of metabolic syndrome have been proposed. One focuses on the accumulation of risk factors, a measure used by the American Heart Association (AHA) and the National Heart, Lung, and Blood Institute (NHLBI); the other focuses on abdominal obesity, a measure used by the International Diabetes Federation (IDF) and the Japanese government. The latter definition takes waist circumference (WC) into consideration as an obligatory component, whereas the former does not. In 2009, the IDF, NHLBI, AHA, and other organizations attempted to unify these criteria; as a result, WC is no longer an obligatory component of those systems, while it remains obligatory in the Japanese criteria. In 2008, a new Japanese cardiovascular screening and education system focused on metabolic syndrome was launched. People undergoing screening are classified into three groups according to the presence of abdominal obesity and the number of metabolic risk factors, and receive health educational support from insurers. This system has yielded several beneficial outcomes: the visibility of metabolic syndrome at the population level has drastically improved; preventive measures have been directed toward metabolic syndrome, which is expected to become more prevalent in future generations; and a post-screening education system has been established. However, several problems with the current system have been identified and are under debate. In this review, we discuss topics related to metabolic syndrome, including (1) the Japanese criteria for metabolic syndrome; (2) metabolic syndrome and the universal health screening and education system; and (3) recent debates about Japanese criteria for metabolic syndrome.